Polanski, who pleaded guilty to raping a 13-year-old girl in California in 1978 and fled before his sentencing, would face extradition to the United States if he appeared in a London court, E! Online reports.
England's highest court ruled Thursday Polanski, 71, who won a best-director Oscar for "The Pianist" in 2003, can testify via a video-conferencing link from his home in Paris.
Polanski contends Vanity Fair slandered his name in a 2002 article that said he seduced a woman soon after the 1969 murder of his wife Sharon Tate. Vanity Fair publisher Condé Nast stands by the story.
Now a French citizen, Polanski has not returned to the United States for fear he would be arrested. Under French law, he cannot be extradited but he would face arrest if he entered Britain or the United States.